Unaudited Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 02, 2021	Sep. 26, 2020	Oct. 02, 2021	Sep. 26, 2020
Revenue:
Revenue	$ 717,240	$ 709,619	$ 1,813,001	$ 1,707,818
Cost of revenue (excluding items shown separately below):
Net cost of revenue	486,936	501,592	1,301,346	1,258,463
General and administrative expenses	47,364	50,972	146,454	132,385
Depreciation, depletion, amortization and accretion	59,082	58,054	173,651	163,760
Gain on sale of property, plant and equipment	(1,159)	(1,616)	(4,331)	(5,747)
Operating (loss) income	125,017	100,617	195,881	158,957
Interest expense	24,134	24,623	72,536	78,049
Loss on debt financings	6,016	4,064	6,016	4,064
Loss (gain) on sale of businesses	113	0	(15,319)	0
Other income, net	(1,137)	(1,226)	(10,721)	(2,753)
Income from operations before taxes	95,891	73,156	143,369	79,597
Income tax expense (benefit)	20,513	(19,613)	33,478	(25,333)
Net income	75,378	92,769	109,891	104,930
Net income attributable to Summit Holdings	1,174	2,039	1,545	2,115
Net income (loss) attributable to Summit Inc/LLC	74,204	90,730	108,346	102,815
Summit Materials, LLC
Revenue:
Revenue	717,240	709,619	1,813,001	1,707,818
Cost of revenue (excluding items shown separately below):
Net cost of revenue	486,936	501,592	1,301,346	1,258,463
General and administrative expenses	47,364	50,972	146,454	132,385
Depreciation, depletion, amortization and accretion	59,082	58,054	173,651	163,760
Gain on sale of property, plant and equipment	(1,159)	(1,616)	(4,331)	(5,747)
Operating (loss) income	125,017	100,617	195,881	158,957
Interest expense	24,134	24,561	72,474	77,807
Loss on debt financings	6,016	4,064	6,016	4,064
Loss (gain) on sale of businesses	113	0	(15,319)	0
Other income, net	(1,137)	(1,226)	(10,721)	(2,753)
Income from operations before taxes	95,891	73,218	143,431	79,839
Income tax expense (benefit)	7,016	(5,106)	12,531	(4,877)
Net income	88,875	78,324	130,900	84,716
Net income attributable to noncontrolling interest in subsidiaries	0	0	0	0
Net income (loss) attributable to Summit Inc/LLC	88,875	$ 78,324	130,900	$ 84,716
Issuers | 5 1/8% Senior Notes, due 2025
Cost of revenue (excluding items shown separately below):
Loss on debt financings	$ 6,016		$ 6,016
Common Class A
Earnings per share of Class A common stock:
Basic (usd per share)	$ 0.63	$ 0.79	$ 0.92	$ 0.90
Diluted (usd per share)	$ 0.62	$ 0.79	$ 0.92	$ 0.90
Weighted average shares of Class A common stock:
Basic (in shares)	118,272,955	114,116,564	117,040,207	113,943,292
Diluted (in shares)	119,291,646	114,472,171	118,360,615	114,457,276
Common Class A And Restricted Stock
Earnings per share of Class A common stock:
Basic (usd per share)	$ 0.63	$ 0.79	$ 0.92	$ 0.90
Weighted average shares of Class A common stock:
Basic (in shares)	118,473,530	114,436,907	117,258,431	114,088,447
Excluding delivery and subcontract revenue
Revenue:
Revenue	$ 662,259	$ 645,246	$ 1,679,270	$ 1,562,892
Cost of revenue (excluding items shown separately below):
Net cost of revenue	431,955	437,219	1,167,615	1,113,537
Excluding delivery and subcontract revenue | Summit Materials, LLC
Revenue:
Revenue	662,259	645,246	1,679,270	1,562,892
Cost of revenue (excluding items shown separately below):
Net cost of revenue	431,955	437,219	1,167,615	1,113,537
Product
Revenue:
Revenue	561,938	540,904	1,443,972	1,334,471
Cost of revenue (excluding items shown separately below):
Net cost of revenue	356,214	354,250	980,045	923,384
Product | Summit Materials, LLC
Revenue:
Revenue	561,938	540,904	1,443,972	1,334,471
Cost of revenue (excluding items shown separately below):
Net cost of revenue	356,214	354,250	980,045	923,384
Service
Revenue:
Revenue	100,321	104,342	235,298	228,421
Cost of revenue (excluding items shown separately below):
Net cost of revenue	75,741	82,969	187,570	190,153
Service | Summit Materials, LLC
Revenue:
Revenue	100,321	104,342	235,298	228,421
Cost of revenue (excluding items shown separately below):
Net cost of revenue	75,741	82,969	187,570	190,153
Delivery and subcontract revenue
Revenue:
Revenue	54,981	64,373	133,731	144,926
Cost of revenue (excluding items shown separately below):
Net cost of revenue	54,981	64,373	133,731	144,926
Delivery and subcontract revenue | Summit Materials, LLC
Revenue:
Revenue	54,981	64,373	133,731	144,926
Cost of revenue (excluding items shown separately below):
Net cost of revenue	$ 54,981	$ 64,373	$ 133,731	$ 144,926